jdb/jbd2: factor out common functions from the jbd[2] header files

The state bits and the lock functions of jbd and jbd2 are
identical.  Share them.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

diff --cc include/linux/jbd.h
Simple merge

diff --cc include/linux/jbd2.h
Simple merge

diff --cc include/linux/jbd_common.h
Simple merge